High-frequency thin-film magnetic bead and preparation method and application thereof

Abstract

The invention relates to a high-frequency thin film magnetic bead and a preparation method and application thereof. The preparation method comprises the steps that a Fe source, a Si source, a B source, a Cu source, a Nb source and a Ga source are smelted into a first alloy ingot according to a formula, then the first alloy ingot and a C source are smelted to prepare a second alloy ingot, the second alloy ingot is prepared into an amorphous alloy strip, and an iron-based nanocrystalline alloy is obtained through magnetic field heat treatment; the method comprises the following steps: mixing an iron-based nanocrystalline alloy and aluminum oxide to form a magnetic mixture, placing the magnetic mixture in a mold provided with a surrounding wire, carrying out pressure forming to obtain a thin-film-shaped magnetic blank, and sintering the thin-film-shaped magnetic blank in an inert gas environment to obtain a magnetic bead blank; and mixing an insulating material with graphite, forming a coating layer on the surface of the magnetic bead blank to obtain a magnetic bead body, and arranging an electrode electrically connected with the surrounding wire on the magnetic bead body to obtain the high-frequency thin-film magnetic bead. According to the invention, the material and the structure of the magnetic bead are optimally designed, so that the high-frequency thin-film magnetic bead with better magnetic performance and smaller volume can be obtained.

Description

Technical Field

[0001] This invention relates to the field of magnetic materials technology, and in particular to a high-frequency thin-film magnetic bead, its preparation method, and its application. Background Technology

[0002] With the rapid development of electronic technology, electromagnetic interference and radio frequency noise problems in electronic devices have become increasingly prominent. These problems not only affect the normal operation of electronic devices, but may also lead to a decline in the performance of electronic devices, a shortened lifespan, or even damage.

[0003] Ferrite beads, as an important electronic component, are widely used to suppress electromagnetic interference and radio frequency noise in electronic devices. However, traditional ferrite beads have the following disadvantages: (1) They exhibit inductive properties at high frequencies, which causes changes in their impedance characteristics, thereby affecting the stability of the circuit operation and the integrity of the main signal; (2) They are prone to saturation, which causes distortion of the current passing through the ferrite bead, thereby generating harmonic interference and interfering with the normal operation of the circuit; (3) They are lacking in terms of volume and height control, and are difficult to apply to special thin devices with strict height requirements. Summary of the Invention

[0004] Therefore, it is necessary to address the above problems by providing a high-frequency thin-film magnetic bead, its preparation method, and its application. By optimizing the design of the material and structure of the magnetic bead, high-frequency thin-film magnetic beads with better magnetic properties and smaller size can be obtained.

[0005] This invention provides a method for preparing high-frequency thin-film magnetic beads, comprising the following steps:

[0006] According to Fe a Si b B c Cu d Nb e Ga f C gThe alloy is prepared by weighing Fe, Si, B, Cu, Nb, Ga, and C sources. First, the Fe, Si, B, Cu, Nb, and Ga sources are smelted for the first time to form a first alloy ingot. Then, the first alloy ingot and the C source are smelted for the second time to form a second alloy ingot. The second alloy ingot is then formed into an amorphous alloy strip, and the strip is used to form a magnetic core. The magnetic core is then subjected to magnetic field heat treatment to obtain an iron-based nanocrystalline alloy, wherein a, b, c, d, and e... f and g represent the atomic percentages of the corresponding elements, 71≤a≤79, 8.5≤b≤14, 7≤c≤13, 0.5≤d≤1.5, 1≤e≤2, 1.3≤f≤2, 0.01≤g≤0.1, and a+b+c+d+e+f+g=100. In the magnetic field heat treatment step, a magnetic field along the width direction of the strip is applied during the heating process, the heat holding process, and the cooling process, and the cooling rate of the cooling process is greater than or equal to 40℃ / s.

[0007] The iron-based nanocrystalline alloy was mixed with alumina to obtain a magnetic mixture;

[0008] The magnetic mixture is placed in a mold with a surrounding wire and pressed to form a thin film magnetic preform.

[0009] The magnetic preform is sintered in an inert gas environment to obtain a magnetic bead preform;

[0010] An insulating material is mixed with graphite, and the surface of the magnetic bead preform is coated to form a coating layer on the surface of the magnetic bead preform, thereby obtaining the magnetic bead body.

[0011] Electrodes electrically connected to the surrounding wire are disposed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

[0012] In one embodiment, the step of subjecting the magnetic core to magnetic field heat treatment satisfies at least one of the following conditions:

[0013] (1) The strength of the magnetic field is 80mT-90mT;

[0014] (2) The temperature of the heat preservation process is 550℃-650℃, and the heat preservation time is 20min-25min;

[0015] (3) The heating rate of the heating process is 10℃ / s-20℃ / s;

[0016] (4) The cooling rate of the cooling process is 40℃ / s-60℃ / s.

[0017] In one embodiment, the thickness of the strip is less than or equal to 14 μm.

[0018] In one embodiment, in the step of mixing the iron-based nanocrystalline alloy with alumina, the particle size of the magnetic mixture is controlled to be 30nm-50nm.

[0019] And / or, the mass ratio of the iron-based nanocrystalline alloy to the alumina is 20:1-40:1.

[0020] In one embodiment, the conductor is made of copper and has a spiral structure.

[0021] In one embodiment, the sintering temperature is 700°C-850°C.

[0022] In one embodiment, the mass ratio of the insulating material to graphite is 3:1 to 5:1;

[0023] And / or, the insulating material is selected from at least one of epoxy resin and polyimide resin.

[0024] In one embodiment, the thickness of the coating layer is 1mm-3mm.

[0025] A high-frequency thin-film magnetic bead prepared by the aforementioned method.

[0026] An electronic component fabricated using the aforementioned high-frequency thin-film magnetic beads.

[0027] This invention prepares an iron-based nanocrystalline alloy through formulation design. During the preparation process, on the one hand, two melting processes ensure more uniform alloy mixing, creating favorable conditions for obtaining smaller and more uniform nanocrystals. The addition of a C source during the second melting reduces the metal oxides generated during the first melting, improving material purity. On the other hand, a transverse magnetic field is applied throughout the magnetic field heat treatment process, effectively improving the kinetics of α-Fe(Si) phase grains during crystallization, inducing grain nucleation, growth, and orientation. Furthermore, by controlling the cooling rate, the magnetic domain structure and grain orientation can be maintained under high-temperature magnetic field conditions. The resulting product has α-Fe(Si) grains with a size of about 5 nm. The small size and range of grains help to improve the magnetic properties of the material. The resulting material has a permeability of over 35,000 at 100 kHz and over 20,000 at 1 MHz. The permeability decay from 100 kHz to 1 MHz is less than 45%. The loss at 100 kHz / 0.2 T is less than 15.0 W / kg and the loss at 10 kHz / 0.5 T is less than 3.5 W / kg. It has both high frequency, high permeability and low loss.

[0028] Furthermore, a magnetic bead preform is prepared by mixing the iron-based nanocrystalline alloy and alumina according to this invention, and a surrounding conductive wire is set inside the preform. Then, a coating layer is prepared on the surface of the preform using graphite and insulating materials, thus optimizing the material and structure of the thin-film magnetic bead. Therefore, the prepared thin-film magnetic beads can be used in the frequency band of 1GHz-4GHz, effectively suppressing electromagnetic interference (EMI) of high-frequency signals, exhibiting excellent high-frequency magnetic properties, and effectively solving the problems of impedance distortion and easy saturation of magnetic beads at high frequencies, improving the stability of circuit operation and the integrity of the main signal. At the same time, it can reduce the resonance problems that may be caused by parasitic capacitance and parasitic inductance of the magnetic beads, reducing radiation interference. In addition, the thickness of the high-frequency thin-film magnetic beads can be as small as 2mm, which can meet the miniaturization requirements of electronic devices. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the high-frequency thin-film magnetic beads prepared in this invention;

[0031] Figure 2 This is a schematic diagram of the structure of the magnetic bead body prepared according to the present invention;

[0032] Figure 3 This is a SEM image of the iron-based nanocrystalline alloy prepared in Example 1 of the present invention.

[0033] In the figure: 1. Electrode; 2. Magnetic bead body; 21. Magnetic bead blank; 22. Wire; 23. Coating layer. Detailed Implementation

[0034] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0036] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0037] Combination Figure 1 and Figure 2 As shown, the method for preparing high-frequency thin-film magnetic beads provided by the present invention includes the following steps:

[0038] S1, preparation of iron-based nanocrystalline alloys;

[0039] S2, the iron-based nanocrystalline alloy is mixed with alumina to obtain a magnetic mixture;

[0040] S3, the magnetic mixture is placed in a mold with a surrounding wire 22 and pressed to form a thin film magnetic blank;

[0041] S4, the magnetic blank is sintered in an inert gas environment to obtain magnetic bead blank 21;

[0042] S5, the insulating material is mixed with graphite and the surface of the magnetic bead preform 21 is coated to form a coating layer 23 on the surface of the magnetic bead preform 21, thus obtaining the magnetic bead body 2.

[0043] S6, an electrode 1 electrically connected to the surrounding wire 22 is provided on the magnetic bead body 2 to obtain a high-frequency thin-film magnetic bead.

[0044] The preparation method of the iron-based nanocrystalline alloy in step S1 includes the following steps:

[0045] According to Fe a Si b B c Cu dNb e Ga f C g The alloy is weighed from Fe source, Si source, B source, Cu source, Nb source, Ga source and C source, where a, b, c, d, e, f and g represent the atomic percentage content of the corresponding elements, 71≤a≤79, 8.5≤b≤14, 7≤c≤13, 0.5≤d≤1.5, 1≤e≤2, 1.3≤f≤2, 0.01≤g≤0.1, and a+b+c+d+e+f+g=100;

[0046] First, the Fe source, Si source, B source, Cu source, Nb source and Ga source are smelted for the first time to make the first alloy ingot. Then, the first alloy ingot and C source are smelted for the second time to make the second alloy ingot.

[0047] The second alloy ingot is made into an amorphous alloy strip, and the strip is made into a magnetic core;

[0048] The magnetic core is subjected to magnetic field heat treatment to obtain an iron-based nanocrystalline alloy. In the magnetic field heat treatment step, a magnetic field along the width direction of the strip is applied during the heating process, the holding process and the cooling process, and the cooling rate of the cooling process is greater than or equal to 40℃ / s.

[0049] This invention designs a formulation for an iron-based nanocrystalline alloy, composed of Fe, Si, B, Cu, Nb, Ga, and C in specific proportions, so that the material composition meets the requirements for miniaturization of electronic components and exhibits excellent flowability during melting and strip preparation.

[0050] Optionally, the Fe source can be elemental iron with a purity ≥ 99.9%, the Si source can be elemental silicon with a purity ≥ 99.9%, the B source can be elemental boron with a purity ≥ 99.9%, the Cu source can be elemental copper with a purity ≥ 99.9%, the Nb source can be elemental niobium with a purity ≥ 99.9%, the Ga source can be elemental gallium with a purity ≥ 99.9%, and the C source can be graphite with a purity ≥ 99.9%.

[0051] First, the Fe source, Si source, B source, Cu source, Nb source and Ga source are smelted for the first time. Then, the first alloy ingot and C source are smelted for the second time. During the second smelting process, the C source can reduce the metal oxides generated during the first smelting. Thus, through two smelting processes, the alloy can be mixed more uniformly and with higher purity, creating favorable conditions for obtaining smaller and more uniform nanocrystals.

[0052] It is understood that the present invention does not limit the process of the first and second melting, and generally uses a vacuum induction furnace.

[0053] Similarly, the present invention does not limit the process of making amorphous alloy strip from the second alloy ingot. Generally, the second alloy ingot is heated and remelted by an induction coil, and then cooled and thrown out by a high-speed rotating copper roller to obtain amorphous alloy strip.

[0054] Optionally, the thickness of the amorphous alloy strip is less than or equal to 14 μm.

[0055] This invention designs the formulation of iron-based nanocrystalline alloys and creates favorable conditions for obtaining smaller and more uniform nanocrystals through two melting processes. By applying a transverse magnetic field throughout the magnetic field heat treatment, the kinetics of α-Fe(Si) phase grains during crystallization can be effectively improved, inducing grain nucleation, growth, and orientation. Furthermore, by controlling the cooling rate, the magnetic domain structure and grain orientation can be maintained when the magnetic field is applied at high temperature. As a result, the α-Fe(Si) grains in the obtained iron-based nanocrystalline alloy reach about 5 nm, and are maintained in the range of approximately 3 nm to 8 nm. The grain size and the range of grain size are both small. Such small and uniform grains help to improve the magnetic properties of the material.

[0056] Therefore, the iron-based nanocrystalline alloy of the present invention achieves a permeability of over 35,000 at a frequency of 100 kHz and over 20,000 at a frequency of 1 MHz. The permeability attenuation from 100 kHz to 1 MHz is less than 45%, the loss at 100 kHz / 0.2T is less than 15.0 W / kg, and the loss at 10 kHz / 0.5T is less than 3.5 W / kg, thus possessing both high frequency, high permeability, and low loss.

[0057] Optionally, in the magnetic field heat treatment step, the magnetic field strength is preferably 80mT-90mT, such as 80mT, 81mT, 82mT, 83mT, 84mT, 85mT, 86mT, 87mT, 88mT, 89mT, 90mT, etc.; the heating rate of the heating process is preferably 10℃ / s-20℃ / s, such as 10℃ / s, 11℃ / s, 12℃ / s, 13℃ / s, 14℃ / s, 15℃ / s, 16℃ / s, 17℃ / s, 18℃ / s, 19℃ / s, 20℃ / s, etc.; and the holding temperature is preferably 550℃-60℃. The temperature is 50℃, such as 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, etc. The holding time is preferably 20min-25min, such as 20min, 21min, 22min, 23min, 24min, 25min, etc. The cooling rate of the cooling process is preferably 40℃ / s-60℃ / s, such as 40℃ / s, 42℃ / s, 45℃ / s, 48℃ / s, 50℃ / s, 52℃ / s, 55℃ / s, 58℃ / s, 60℃ / s, etc.

[0058] Optionally, Fe can be used first. a Si b B c Cu d Nb e Ga f C g The magnetic core is treated with amorphous alloy powder and then subjected to magnetic field heat treatment, which can further improve the material's magnetic permeability and other properties. The Fe... a Si b B c Cu d Nb e Ga f C g Amorphous alloy powder is obtained by crushing the second alloy ingot and / or the strip, and the processing method is not limited, such as placing the magnetic core in Fe a Si b B c Cu d Nb e Ga f C g Amorphous alloy powder is vibrated to make Fe a Si b B c Cu d Nb e Ga f C g Amorphous alloy powder is used to fill the gaps in the magnetic core.

[0059] In this invention, the magnetic bead preform 21 is prepared by mixing alumina with the iron-based nanocrystalline alloy. This not only controls the application frequency band and magnetic properties of the thin-film magnetic beads, but also reduces heat loss by utilizing the heat dissipation effect of alumina.

[0060] In step S2, the mass ratio of the iron-based nanocrystalline alloy to alumina is preferably 20:1-40:1, such as 20:1, 22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 34:1, 36:1, 38:1, 40:1, etc., so that the application frequency band and magnetic properties of the thin film magnetic beads can be further controlled by controlling the mass ratio of alumina to iron-based nanocrystalline alloy.

[0061] Optionally, in the step of mixing the iron-based nanocrystalline alloy with alumina, the particle size of the magnetic mixture is controlled to be 30nm-50nm by grinding or other methods, such as 30nm, 35nm, 40nm, 45nm, 50nm, etc. This is beneficial to increase the anisotropy of the magnetic crystal, improve coercivity, optimize particle size distribution, reduce magnetic domain wall movement resistance, and improve remanence and maximum magnetic energy product.

[0062] In step S3, when the magnetic mixture is placed in a mold with a surrounding wire 22 and pressed to form a thin film magnetic blank, the magnetic mixture is pressed and formed and the wire 22 is wrapped inside to form a magnetic blank. At this time, the two ends of the wire 22 can extend out of the magnetic blank for connection with the electrode 1.

[0063] Optionally, the winding structure of the conductor 22 can be arranged in various ways. For example, flat copper wire can be used in a spiral structure to increase the length of the high-frequency current path, thereby improving the noise suppression effect. At the same time, the conductor 22 can be arranged along the length direction of the magnetic blank, thereby increasing the length of the conductor 22.

[0064] In step S4, when the magnetic blank is sintered in an inert gas environment, the inert gas can be selected from nitrogen, argon, etc., and the sintering temperature is preferably 700℃-850℃, such as 700℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, etc., which is beneficial to eliminate pores in the magnetic blank and reduce internal defects, thereby forming a continuous and dense structure. After sintering is completed, it is cooled to room temperature to obtain magnetic bead blank 21.

[0065] In step S5, when the magnetic bead blank 21 is coated with a mixture of insulating material and graphite, coating or spraying can be used. The insulating material is beneficial for electrical isolation, and the graphite is beneficial for reducing the temperature rise of the magnetic bead during operation and reducing the risk of saturation of the magnetic bead. After the coating layer 23 is formed, the coating layer 23 can protect the overall structure.

[0066] Optionally, the thickness of the coating layer 23 is preferably 1mm-3mm, such as 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.

[0067] Optionally, the mass ratio of the insulating material to graphite is preferably 3:1-5:1, such as 3:1, 4:1, 5:1, etc., which is beneficial to forming a better protective effect. The insulating material can be selected from epoxy resin, polyimide resin, etc.

[0068] In step S6, the electrodes 1 are preferably disposed at both ends of the length direction of the magnetic bead body 2 and electrically connected to the wires 22 extending out of the magnetic bead body 2.

[0069] Therefore, the iron-based nanocrystalline alloy prepared in this invention is mixed with alumina to prepare a magnetic bead preform 21, and a surrounding wire 22 is set inside the magnetic bead preform 21. Then, a coating layer 23 is prepared on the surface of the magnetic bead preform 21 using graphite and insulating materials. Overall, the material and structure of the thin film magnetic bead are optimized, so that the application frequency band of the prepared thin film magnetic bead reaches 1GHz-4GHz. It can effectively suppress electromagnetic interference (EMI) of high-frequency signals and has excellent high-frequency magnetic properties. In addition, it can effectively solve the problems of impedance characteristic distortion and easy saturation of magnetic beads at high frequencies, improve the stability of circuit operation and the integrity of the main signal, and reduce the resonance problems that may be caused by parasitic capacitance and parasitic inductance of magnetic beads, and reduce radiation interference. In addition, the thickness of the high-frequency thin film magnetic bead can be as small as 2mm, which can meet the requirements of miniaturization of electronic devices.

[0070] This invention also provides a high-frequency thin-film magnetic bead, which is prepared by the above-described preparation method, combined with... Figure 1 and Figure 2 As shown, the high-frequency thin-film magnetic bead includes a magnetic bead body 2 and an electrode 1 electrically connected to the magnetic bead body 2. The magnetic bead body 2 includes a magnetic bead preform 21 and a coating layer 22 covering the surface of the magnetic bead preform 21. The magnetic bead preform 21 is made of iron-based nanocrystalline alloy and alumina. A circumferential wire 22 is also provided inside the magnetic bead preform 21. The wire 22 extends out of the magnetic bead preform 21 and is electrically connected to the electrode 1.

[0071] The present invention also provides an electronic device made using the aforementioned high-frequency thin-film magnetic beads.

[0072] The following specific embodiments will further illustrate the high-frequency thin-film magnetic beads, their preparation method, and their applications.

[0073] Example 1

[0074] According to Fe 75.2 Si 10.4 B 10 Cu 1.2 Nb 1.44 Ga 1.71 C 0.05 The alloy comprises iron (≥99.9% purity), silicon (≥99.9% purity), boron (≥99.9% purity), copper (≥99.9% purity), niobium (≥99.9% purity), gallium (≥99.9% purity), and graphite (≥99.9% purity).

[0075] First, place elemental iron, silicon, boron, copper, niobium, and gallium in a crucible within a vacuum induction furnace, and evacuate to a vacuum level of 5 × 10⁻⁶. -2Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make the first alloy liquid. Then the first alloy liquid is poured into a cooling mold to cool and obtain the first alloy ingot.

[0076] Then the first alloy ingot and graphite were placed back into the crucible of the vacuum induction furnace, and a vacuum was drawn to 10. -3 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make a second alloy liquid. The second alloy liquid is then poured into a cooling mold to cool and obtain a second alloy ingot.

[0077] The second alloy ingot is mechanically crushed and loaded into a quartz tube. The second alloy ingot is heated and remelted by an induction coil. Then it is cooled and thrown out by a high-speed rotating copper roller to obtain an amorphous alloy strip with a thickness of 13μm, which is then wound into a magnetic core.

[0078] The magnetic core was placed in the powder obtained from the crushing of the second alloy ingot and vibrated for 10 minutes. Then, it was placed in a magnetic field furnace for magnetic field heat treatment. In this process, a vacuum was first created, the magnetic field direction was set to the width direction of the strip, and the magnetic field strength was 85 mT. The temperature was then increased to 600℃ at a rate of 15℃ / min and held at 600℃ for 25 minutes. After holding, heating was stopped, and the strip was rapidly cooled at a rate of 50℃ / min to obtain an iron-based nanocrystalline alloy. Figure 3 As shown, the iron-based nanocrystalline alloy obtained by this invention has α-Fe(Si) phase grains with a size of 3nm-8nm grown on an amorphous substrate.

[0079] Iron-based nanocrystalline alloy and alumina were mixed at a mass ratio of 30:1 and ground to a particle size of 40 nm to obtain a magnetic mixture.

[0080] The magnetic mixture is placed in a mold with a surrounding copper wire and pressed to form a thin film magnetic preform.

[0081] The magnetic preform was sintered in an argon atmosphere at a temperature of 750°C for 30 minutes, and then naturally cooled to obtain the magnetic bead preform.

[0082] Epoxy resin and graphite are mixed in a mass ratio of 4:1 to form a mixture, and then the mixture is used to coat the surface of the magnetic bead preform to obtain the magnetic bead body.

[0083] Electrodes electrically connected to a surrounding copper wire are placed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

[0084] Example 2

[0085] According to Fe 71.2 Si 13.8 B 12 Cu 0.5 Nb 1.1Ga 1.39 C 0.01 The alloy comprises iron (≥99.9% purity), silicon (≥99.9% purity), boron (≥99.9% purity), copper (≥99.9% purity), niobium (≥99.9% purity), gallium (≥99.9% purity), and graphite (≥99.9% purity).

[0086] First, place elemental iron, silicon, boron, copper, niobium, and gallium in a crucible within a vacuum induction furnace, and evacuate to a vacuum level of 5 × 10⁻⁶. -2 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make the first alloy liquid. Then the first alloy liquid is poured into a cooling mold to cool and obtain the first alloy ingot.

[0087] Then the first alloy ingot and graphite were placed back into the crucible of the vacuum induction furnace, and a vacuum was drawn to 10. -3 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make a second alloy liquid. The second alloy liquid is then poured into a cooling mold to cool and obtain a second alloy ingot.

[0088] The second alloy ingot is mechanically crushed and loaded into a quartz tube. The second alloy ingot is heated and remelted by an induction coil. Then it is cooled and thrown out by a high-speed rotating copper roller to obtain an amorphous alloy strip with a thickness of 14μm, which is then wound into a magnetic core.

[0089] The magnetic core was placed in the powder obtained by crushing the second alloy ingot and vibrated for 10 minutes. Then it was placed in a magnetic field furnace for magnetic field heat treatment. In the magnetic field heat treatment step, a vacuum was first drawn, the magnetic field direction was set to the width direction of the strip, the magnetic field strength was 80 mT, and then the temperature was raised to 550℃ at a rate of 10℃ / min. The temperature was held at 550℃ for 25 minutes. After the holding time was completed, the heating was stopped and the temperature was rapidly cooled at a rate of 40℃ / min to obtain the iron-based nanocrystalline alloy.

[0090] Iron-based nanocrystalline alloy and alumina were mixed at a mass ratio of 20:1 and ground to a particle size of 30 nm to obtain a magnetic mixture.

[0091] The magnetic mixture is placed in a mold with a surrounding copper wire and pressed to form a thin film magnetic preform.

[0092] The magnetic preform was sintered in an argon atmosphere at a temperature of 700°C for 30 minutes, and then naturally cooled to obtain the magnetic bead preform.

[0093] Polyimide resin and graphite are mixed in a mass ratio of 3:1 to form a mixture, and then the mixture is used to coat the surface of the magnetic bead preform to obtain the magnetic bead body.

[0094] Electrodes electrically connected to a surrounding copper wire are placed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

[0095] Example 3

[0096] According to Fe 76.5 Si 9.8 B 8.1 Cu 1.5 Nb2Ga2C 0.1 The alloy comprises iron (≥99.9% purity), silicon (≥99.9% purity), boron (≥99.9% purity), copper (≥99.9% purity), niobium (≥99.9% purity), gallium (≥99.9% purity), and graphite (≥99.9% purity).

[0097] First, place elemental iron, silicon, boron, copper, niobium, and gallium in a crucible within a vacuum induction furnace, and evacuate to a vacuum level of 5 × 10⁻⁶. -2 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make the first alloy liquid. Then the first alloy liquid is poured into a cooling mold to cool and obtain the first alloy ingot.

[0098] Then the first alloy ingot and graphite were placed back into the crucible of the vacuum induction furnace, and a vacuum was drawn to 10. -3 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make a second alloy liquid. The second alloy liquid is then poured into a cooling mold to cool and obtain a second alloy ingot.

[0099] The second alloy ingot is mechanically crushed and loaded into a quartz tube. The second alloy ingot is heated and remelted by an induction coil. Then it is cooled and thrown out by a high-speed rotating copper roller to obtain an amorphous alloy with a thickness of 13.5 μm, which is then wound into a magnetic core.

[0100] The magnetic core was placed in the powder obtained by crushing the second alloy ingot and vibrated for 10 minutes. Then it was placed in a magnetic field furnace for magnetic field heat treatment. In the magnetic field heat treatment step, a vacuum was first drawn, the magnetic field direction was set to the width direction of the strip, the magnetic field strength was 90 mT, and then the temperature was raised to 650℃ at a rate of 20℃ / min. The temperature was held at 650℃ for 20 minutes. After the holding time was completed, the heating was stopped and the temperature was rapidly cooled at a rate of 60℃ / min to obtain the iron-based nanocrystalline alloy.

[0101] Iron-based nanocrystalline alloy and alumina were mixed at a mass ratio of 40:1 and ground to a particle size of 50 nm to obtain a magnetic mixture.

[0102] The magnetic mixture is placed in a mold with a surrounding copper wire and pressed to form a thin film magnetic preform.

[0103] The magnetic preform was sintered in an argon atmosphere at a temperature of 850°C for 30 minutes, and then naturally cooled to obtain the magnetic bead preform.

[0104] Epoxy resin and graphite are mixed in a mass ratio of 5:1 to form a mixture, and then the mixture is used to coat the surface of the magnetic bead preform to obtain the magnetic bead body.

[0105] Electrodes electrically connected to a surrounding copper wire are placed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

[0106] Example 4

[0107] According to Fe 79 Si 8.7 B 7.3 Cu 1.3 Nb 1.7 Ga 1.94 C 0.06 The alloy comprises iron (≥99.9% purity), silicon (≥99.9% purity), boron (≥99.9% purity), copper (≥99.9% purity), niobium (≥99.9% purity), gallium (≥99.9% purity), and graphite (≥99.9% purity).

[0108] First, place elemental iron, silicon, boron, copper, niobium, and gallium in a crucible within a vacuum induction furnace, and evacuate to a vacuum level of 5 × 10⁻⁶. -2 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make the first alloy liquid. Then the first alloy liquid is poured into a cooling mold to cool and obtain the first alloy ingot.

[0109] Then the first alloy ingot and graphite were placed back into the crucible of the vacuum induction furnace, and a vacuum was drawn to 10. -3 Pa, then nitrogen gas is introduced and electric heating is applied to melt all the raw materials to make a second alloy liquid. The second alloy liquid is then poured into a cooling mold to cool and obtain a second alloy ingot.

[0110] The second alloy ingot is mechanically crushed and loaded into a quartz tube. The second alloy ingot is heated and remelted by an induction coil. Then it is cooled and thrown out by a high-speed rotating copper roller to obtain an amorphous alloy strip with a thickness of 12μm, which is then wound into a magnetic core.

[0111] The magnetic core was placed in the powder obtained by crushing the second alloy ingot and vibrated for 10 minutes. Then it was placed in a magnetic field furnace for magnetic field heat treatment. In the magnetic field heat treatment step, a vacuum was first drawn, the magnetic field direction was set to the width direction of the strip, the magnetic field strength was 85mT, and then the temperature was raised to 620℃ at a rate of 15℃ / min. The temperature was held at 620℃ for 22 minutes. After the holding time was completed, the heating was stopped and the temperature was rapidly cooled at a rate of 52℃ / min to obtain the iron-based nanocrystalline alloy.

[0112] Iron-based nanocrystalline alloy and alumina were mixed at a mass ratio of 40:1 and ground to a particle size of 45 nm to obtain a magnetic mixture.

[0113] The magnetic mixture is placed in a mold with a surrounding copper wire and pressed to form a thin film magnetic preform.

[0114] The magnetic preform was sintered in an argon atmosphere at a temperature of 800℃ for 30 minutes, and then naturally cooled to obtain the magnetic bead preform.

[0115] Polyimide resin and graphite are mixed in a mass ratio of 4:1 to form a mixture, and then the mixture is used to coat the surface of the magnetic bead preform to obtain the magnetic bead body.

[0116] Electrodes electrically connected to a surrounding copper wire are placed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

[0117] Comparative Example 1

[0118] The only difference between Comparative Example 1 and Example 1 is that, according to Fe... 76.91 Si 10.4 B 10 Cu 1.2 Nb 1.44 C 0.05 The alloy consists of elemental iron (≥99.9%), elemental silicon (≥99.9%), elemental boron (≥99.9%), elemental copper (≥99.9%), elemental niobium (≥99.9%), and elemental graphite (≥99.9%).

[0119] Comparative Example 2

[0120] The only difference between Comparative Example 2 and Example 1 is that, according to Fe... 75.91 Si 10.4 B 10 Cu 1.2 Nb 1.44 Ga1C 0.05 The alloy comprises iron (≥99.9% purity), silicon (≥99.9% purity), boron (≥99.9% purity), copper (≥99.9% purity), niobium (≥99.9% purity), gallium (≥99.9% purity), and graphite (≥99.9% purity).

[0121] Comparative Example 3

[0122] The only difference between Comparative Example 3 and Example 1 is that, according to Fe... 75.25 Si 10.4 B 10 Cu 1.2 Nb 1.44 Ga 1.71The alloy consists of elemental iron (≥99.9%), elemental silicon (≥99.9%), elemental boron (≥99.9%), elemental copper (≥99.9%), elemental niobium (≥99.9%), and elemental gallium (≥99.9%).

[0123] Comparative Example 4

[0124] The only difference between Comparative Example 4 and Example 1 is that elemental iron, elemental silicon, elemental boron, elemental copper, elemental niobium, elemental gallium, and graphite are melted simultaneously to obtain an alloy ingot.

[0125] Comparative Example 5

[0126] The only difference between Comparative Example 5 and Example 1 is that after the heat preservation was completed, heating was stopped and the magnetic field was turned off, and then the temperature was rapidly cooled at a rate of 50°C / min.

[0127] Comparative Example 6

[0128] The only difference between Comparative Example 6 and Example 1 is that after the heat preservation was completed, heating was stopped and cooling was carried out at a rate of 30°C / min.

[0129] Comparative Example 7

[0130] The only difference between Comparative Example 7 and Example 1 is that iron oxide is used instead of aluminum oxide.

[0131] Comparative Example 8

[0132] The only difference between Comparative Example 8 and Example 1 is that no alumina was added.

[0133] Comparative Example 9

[0134] The only difference between Comparative Example 9 and Example 1 is that no surface coating treatment was performed.

[0135] Comparative Example 10

[0136] The only difference between Comparative Example 10 and Example 1 is that aluminum oxide was used instead of graphite to mix with epoxy resin, and the magnetic bead preform was surface coated.

[0137] The iron-based nanocrystalline alloy and high-frequency thin-film magnetic beads obtained above were subjected to performance tests, and the results are shown in Tables 1 and 2.

[0138] Table 1

[0139]

[0140] Table 2

[0141]

[0142] As shown in Table 1, by designing the formulation of the iron-based nanocrystalline alloy and adjusting the melting method and magnetic field heat treatment method, small and uniform α-Fe(Si) phase grains can be obtained, thus enabling the iron-based nanocrystalline alloy to have both high frequency, high magnetic permeability and low loss.

[0143] As shown in Table 2, the iron-based nanocrystalline alloy prepared by this invention is mixed with alumina to prepare magnetic bead preforms. A surrounding conductive wire is then placed inside the magnetic bead preform, and a coating layer is prepared on the surface of the magnetic bead preform using graphite and insulating materials. This allows the prepared thin-film magnetic beads to achieve an application frequency band of 1GHz-4GHz, effectively suppressing electromagnetic interference (EMI) of high-frequency signals. They exhibit excellent high-frequency magnetic properties, effectively solving the problems of impedance distortion and saturation of magnetic beads at high frequencies, improving the stability of circuit operation and the integrity of the main signal. Simultaneously, it reduces resonance problems that may be caused by parasitic capacitance and inductance of the magnetic beads, reducing radiated interference.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing high-frequency thin-film magnetic beads, characterized in that, Includes the following steps: According to Fe a Si b B c Cu d Nb e Ga f C g The alloy is prepared by weighing Fe, Si, B, Cu, Nb, Ga, and C sources. First, the Fe, Si, B, Cu, Nb, and Ga sources are smelted for the first time to form a first alloy ingot. Then, the first alloy ingot and the C source are smelted for the second time to form a second alloy ingot. The second alloy ingot is then formed into an amorphous alloy strip, and the strip is used to form a magnetic core. The magnetic core is then subjected to magnetic field heat treatment to obtain an iron-based nanocrystalline alloy, wherein a, b, c, d, and e... f and g represent the atomic percentages of the corresponding elements, 71≤a≤79, 8.5≤b≤14, 7≤c≤13, 0.5≤d≤1.5, 1≤e≤2, 1.3≤f≤2, 0.01≤g≤0.1, and a+b+c+d+e+f+g=100. In the magnetic field heat treatment step, a magnetic field along the width direction of the strip is applied during the heating process, the heat holding process, and the cooling process, and the cooling rate of the cooling process is greater than or equal to 40℃ / s. The iron-based nanocrystalline alloy was mixed with alumina to obtain a magnetic mixture; The magnetic mixture is placed in a mold with a surrounding wire and pressed to form a thin film magnetic preform. The magnetic preform is sintered in an inert gas environment to obtain a magnetic bead preform; An insulating material is mixed with graphite, and the surface of the magnetic bead preform is coated to form a coating layer on the surface of the magnetic bead preform, thereby obtaining the magnetic bead body. Electrodes electrically connected to the surrounding wire are disposed on the magnetic bead body to obtain a high-frequency thin-film magnetic bead.

2. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The step of subjecting the magnetic core to magnetic field heat treatment satisfies at least one of the following conditions: (1) The strength of the magnetic field is 80mT-90mT; (2) The temperature of the heat preservation process is 550℃-650℃, and the heat preservation time is 20min-25min; (3) The heating rate of the heating process is 10℃ / s-20℃ / s; (4) The cooling rate of the cooling process is 40℃ / s-60℃ / s.

3. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The thickness of the strip is less than or equal to 14 μm.

4. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, In the step of mixing the iron-based nanocrystalline alloy with alumina, the particle size of the magnetic mixture is controlled to be 30nm-50nm. And / or, the mass ratio of the iron-based nanocrystalline alloy to the alumina is 20:1-40:

1.

5. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The conductor is made of copper and has a spiral structure.

6. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The sintering temperature is 700℃-850℃.

7. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The mass ratio of the insulating material to graphite is 3:1 to 5:1; And / or, the insulating material is selected from at least one of epoxy resin and polyimide resin.

8. The method for preparing high-frequency thin-film magnetic beads according to claim 1, characterized in that, The thickness of the coating layer is 1mm-3mm.

9. A high-frequency thin-film magnetic bead prepared by the method of preparing a high-frequency thin-film magnetic bead according to any one of claims 1 to 8.

10. An electronic device fabricated using the high-frequency thin-film magnetic beads as described in claim 9.

Images